Julie A. Howe

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Biofortification of maize with beta-carotene has the potential to improve vitamin A status in vitamin A deficient populations where maize is a staple crop. Accurate assessment of provitamin A carotenoids in maize must be performed to direct breeding efforts. The objective was to evaluate carotenoid extraction methods and determine essential steps for use in(More)
Maize has been targeted for biofortification with provitamin A carotenoids through traditional breeding. Two studies were conducted in gerbils to evaluate factors that may affect provitamin A activity. Maize diets had equal theoretical concentrations of vitamin A (VA) assuming 100% bioefficacy. Study 1 ( n = 57) varied the ratio of beta-cryptoxanthin and(More)
Fruits and vegetables are rich sources of provitamin A carotenoids. We evaluated the vitamin A (VA) bioefficacy of a whole foods supplement (WFS) and its constituent green vegetables (Study 1) and a variety of fruits with varying ratios of provitamin A carotenoids (Study 2) in VA-depleted Mongolian gerbils (n = 77/study). After feeding a VA-deficient diet(More)
Maize with enhanced provitamin A carotenoids (biofortified), accomplished through conventional plant breeding, maintains vitamin A (VA) status in Mongolian gerbils (Meriones unguiculatus). Two studies in gerbils compared the VA value of beta-cryptoxanthin with beta-carotene. Study 1 (n 47)examined oil supplements and study 2 (n 46) used maize with enhanced(More)
Efforts to increase beta-carotene in cassava have been successful, but the ability of high-beta-carotene cassava to prevent vitamin A deficiency has not been determined. Two studies investigated the bioefficacy of provitamin A in cassava and compared the effects of carotenoid content and variety on vitamin A status in vitamin A-depleted Mongolian gerbils(More)
The natural isotopic composition of 13C and 12C in tissues is largely determined by the diet. Sources of provitamin A carotenoids (e.g., vegetables) typically have a lower 13C to 12C ratio (13C:12C) than preformed vitamin A sources (i.e., dairy and meat) from corn-fed animals, which are prevalent in the US. The 13C:12C of serum retinol (13C:12C-retinol) was(More)
The vitamin A (VA) value of carotenoids from fruits and vegetables is affected by many factors. This study determined the VA value of -carotene isolated from carrots compared with -carotene and retinyl acetate supplements fed to Mongolian gerbils (Meriones unguiculatus). Gerbils (n 38) were fed a VA-free diet for 4 wk. At baseline, 6 gerbils were killed to(More)
Hypervitaminosis A is increasingly a public health concern, and thus noninvasive quantitative methods merit exploration. In this study, we applied the (13)C-retinol isotope dilution test to a nonhuman primate model with excessive liver stores. After baseline serum chemistries, rhesus macaques (Macaca mulatta; n = 16) were administered 3.5 mumol(More)
Efforts to biofortify maize with provitamin A carotenoids have been successful, but the impact on vitamin A (VA) status has not been determined. We conducted two studies that investigated the bioefficacy of provitamin A carotenoids from maize and compared maize percentage and carotenoid concentrations on VA status in VA-depleted Mongolian gerbils (Meriones(More)
The vitamin A (VA) value of carotenoids from fruits and vegetables is affected by many factors. This study determined the VA value of alpha-carotene isolated from carrots compared with beta-carotene and retinyl acetate supplements fed to Mongolian gerbils (Meriones unguiculatus). Gerbils (n = 38) were fed a VA-free diet for 4 wk. At baseline, 6 gerbils were(More)
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